Did James Buchanan execute his office faithfully when South Carolina tryed to leave the Union? We have to give him the benifit of the doubt that he did. I myself do not know if he did something or not? Could he have done anything anyway because of the short time he had in office before the Lincoln administration?

Short time he had in office? He had over three months before Lincoln took office from the election of 1860. It wasn't until the '30s that the date of the Presidential Inauguration was moved to January 20th. From Washington's second inauguration through to FDR's second every elected president was sworn in March 4th unless the 4th fell on a Sunday. The entire first wave of secession happened on his watch. The Confederacy was formed while he was president. By saying Lincoln had the Constitutional duty to preserve the union then we also have to say Buchannon and the Constitutional duty to prevent it from happening. Most things I've seen have said that Buchannon decided to leave it up to Lincoln to handle. It's a little over two months since SC secedes before Lincoln is sworn in, 74 days in fact. That 118 days after the election. 74 days isn't exactly a short time.